Today, high buildings are almost invariably provided with several elevator banks, each of which can transport passengers to different parts/different floors and zones in the building. One elevator bank typically comprises 4–8 elevators. The operation of the elevators comprised in the elevator bank is controlled by a group control system of the elevator bank, which receives landing calls for the elevators in the elevator bank. Landing calls are issued to the group control system via landing call input devices, such as landing call keys, or they are virtual calls obtained from a data processing system. In addition to landing call input devices, calls can be given in most elevator systems by means of car call input devices provided in the elevator cars, but these calls are generally not transmitted to the group control system of the elevator bank. The landing call input devices on different floors are generally up/down call keys placed outside the elevator bank, which are common to all the elevators in the elevator bank, although in some systems the landing call input devices on the floors are floor call devices used to give a desired destination floor. The landing call keys used in the entrance hall are invariably floor call keys.
After the calls have been transmitted to the group control system by any method, the said group control system will allocate these group calls to the elevator control systems comprised in the elevator group by utilizing a suitable control algorithm. In general, the control algorithm aims at minimizing the passengers' call time and/or journey time. After this, the elevator control systems carry out the group calls assigned (allocated) to them, yet also taking the car calls issued from the elevator car into account. In some cases the elevator group is implemented using only elevator group specific landing call input devices at the floors and lobbies but no car call input devices in the elevator cars. Thus, in these control systems, no car calls are given at all; instead, all calls are landing calls, which the group control system receives, processes and distributes to the lower-level elevator control systems.
In this context, “elevator group” and “elevator bank” refer to two or more elevators which are situated close to each other and have common landing call input devices and whose operation is coordinated by a common group control system.
“Landing call” here refers to a call transmitted to the group control system from outside the elevator car. A landing call may also consist of a completely virtual call produced by a data processing system.
“Car call” refers to a call issued from inside the elevator car.
“Call” in general again refers to a landing call, car call or virtual call. A virtual call is a call produced by a data processing system and is therefore not necessarily related to calls produced by actual persons. However, virtual calls are generally produced by a logic that emulates calls given by actual persons as realistically as possible.
The ease of transport and the length of total traveling time from an elevator lobby in a building having one or more elevator banks to different floors are dependent first on the call time, i.e. the time from the instant the passenger has given an elevator call until the instant when an elevator going in the right direction arrives at the passenger's floor. In addition, the length of the total traveling time on the elevator ride time, i.e. the time from the instant the person enters the elevator to the instant when the person arrives at the desired destination floor. Moreover, the total traveling time is often increased by a time of transition from the entrance hall to the right elevator bank and elevator especially in large buildings. The transition time may be fairly long if the building has several elevator banks of which the person must first select and identify the right elevator bank and then find in the respective elevator bank the fastest elevator going to the destination floor. The traveling time and the call time can be reduced by technical means, such as by developing the control algorithm used in the group control system, whereas the transition time can not be reduced by merely developing the group control system of the elevator bank, because it involves a time delay that is primarily dependent on the spaces in the building and the quality of the guidance systems intended to guide the passengers.
In a guidance system known from specification “TMS9900 System with Destination Consultation Stations”, written by Marja-Liisa Siikonen and Johannes De Jong, a display board placed above each elevator in the elevator bank and showing the floors to which the respective elevator is going is used to reduce the transition time.
However, a display board like this does not eliminate the problem arising from the circumstance that a person cannot find the right elevator bank at all in a complex building having several elevator banks or that the passenger further has to select the right elevator from among a relatively large number of elevators in a bank.